Trip control apparatus of circuit breaker

Abstract

When a voltage (V) of a D.C. power source having an internal resistance (5a) exceeds an "exciting voltage" (FIG. 2), transistors (21, 28 and 33) turn ON, and a transistor (30) turns OFF, and then a tripping winding 16 is excited to close a circuit breaker; on the other hand when the voltage (V) is lowered under a "tripping voltage", the transistor (33) turns OFF and the transistor (30) turns ON, and thereby a load resistor (31) which is less than a resistance 34 of the tripping winding 16 is connected to the D.C. power source; consequently, the voltage V is further lowered by the internal resistance (5a), and a voltage difference is produced between the exciting voltage and the tripping voltage, thus making a "hysteresis characteristic" between the exciting voltage and the tripping voltage.

What is claimed is: 
     
       1. A trip control apparatus of a circuit breaker comprising: voltage detecting means for issuing an output signal in a voltage range above a predetermined voltage of a D.C. power source having an internal resistance,   first switch means to be closed by said output signal of said voltage detecting means,   a load resistance to be connected to said D.C. Power source by closing of said first switch means   second switch means to be closed by opening of said first switch means and to be opened by closing of said first switch means, and   a tripping coil of said circuit breaker having a resistance larger than said load resistance and to be connected to said D.C. power source by closing of said second switch means.   
     
     
       2. A trip control apparatus as claimed in claim 1, wherein said first switch means and load resistance are arranged in series with each other, wherein said second switch means and tripping coil are arranged in series with each other, and wherein the series combination of the first switch means and load resistance is arranged in parallel with the series combination of the second switch means and the tripping coil.